Pull-operated switch with arc snuffer



June 25, 1956 G. B. BENANDER 2,752,442

PULL-OPERATED SWITCH WITH ARC SNUFFER Filed March 30, 1955 2Sheets-Sheet 1 HA9 Attorney J1me 1956 G. B. BENANDER PULL-OPERATEDSWITCH WITH ARC SNUFFER 2 Sheet s-Sheet 2 Filed March 30, 1955 [)7 van t02". Ge 0236 B B enanaen PULL-OPERATED SWITCH WITH ARC SNUFFER George B.Benander, Oaklawn, R. I., assignor to General Electric Company, acorporation of New York Application March 30, 1955, Serial No. 497,902

Claims. (Cl. ZOO-51.15)

The present invention relates to a pull-chain-operated electric switchand in particular to a switch having a ratchet-operated mechanism.

Pulloperated switches commonly employ a pull chain to actuate a ratchetmechanism for making and breaking the circuit to the switch. At thepresent time these switches are made and used in huge quantities;therefore, it has always been desirable to simplify the design as newtechniques and materials are discovered and made available. The firstimprovement that has been made in the present design is the addition ofan arc snufiing means in cooperation with the edgewise blades of therotary contactor of the switch which considerably extends the life ofthe switch. While there are other switch mechanisms on the market whichhave the same high electrical rating as the present switch, they aremuch more expensive to manufacture which in turn dictates a considerableprice differential over the lower rated constructions. The improvementof the present invention is primarily in the configuration of the rotarycontactor having blades disposed edgewise with relation to the fixedcontacts so that narrow grooves may be formed between the fixed contactsto prevent an are from spreading and eventually burning the contactingparts. This feature is considered to be an important part of the presentinvention for it brings about unexpected results which enable the switchto have a higher electrical rating at a lower cost than has beenpossible heretofore.

Another advantage of the present invention is that all of the separateswitch parts may be assembled in onehalf of the hollow switch housingwhich is closed by simply placing the remaining half of the housing incooperative engagement therewith, and finally in connecting the twohousing parts together. This is an important consideration for it mustbe remembered that this switch will be made literally by the millionseach year. Since the design does not require the housing parts to beturned over in order to complete the assembly, it is much simpler tohandle and easier to assemble. It is interesting to note that the designof the present invention is to replace an old construction made by thepresent assignee which contained a total of 22 parts whereas this designcontains only 14 parts or 36% less parts. T 0 give an example of thesaving, it 3,000,000 switches were to be manufactured per year, thepresent design would eliminate the manufacture and handling of24,000,000 parts.

The principal object of this invention is to provide a pull-operatedelectric switch having an arc-snutfing means to increase the electricalrating and the useful life of the switch.

A further object of this invention is to provide a pulloperated switchwith a rotary contactor having edgewise blades for making connectionwith the fixed contacts of the switch.

A further object of this invention is to provide an electric switchhaving a ratchet type mechanism wherein edgewise blades of the rotarycontactor may be seated ited States Patent ICC within narrow grooveswhich serve to extinguish the are between the contactor and the fixedcontacts of the switch.

A further object of this invention is to provide a ratchet type switchmechanism having a minimum number of parts which are simple in designand easy to assemble within a short time on a mass production basis.

My invention will be better understood from the following descriptiontaken in connection with the accompanying drawing and its scope will bepointed out in the appended claims.

Figure 1 is an elevational view of a socket interior having a pull-chainoperated switch mechanism embodying my invention.

Figure 2 is a back elevational view of the socket interior of Figure 1.

Figure 3 is a view of the socket interior of Figure l with the screwshell and one-half of the insulating housing removed to show therelationship of the switch parts mounted therein.

Figure 4 is a left end elevational view of the socket interior of Figure1.

Figure 5 is a top plan view of the socket interior of Figure 2.

Figure 6 is a bottom plan view of the socket interior of Figure 2.

Figure 7 is an exploded perspective view of a socket interior embodyingmy invention.

Referring in detail to the drawing, Figure 1 shows a lamp socketinterior 10 comprising a metal screw shell 11 and a hollow split housing12 of suitable insulating material for enclosing a ratchet-type switchmechanism. Looking at Figure 7 of the drawing, the split hollow housing12 is formed of two recessed molded pieces 13 and 14 of suitablephenolic insulating material. The part 13 will be referred to as a basemember since all of the switch parts are assembled therein, while thepart 14 serves as a cover member to complete the enclosure of the switchmechanism. There is an integral stud member 15 molded in the base 13which serves as the focal point of the fixed and movable contacts of theratchet mechanism. Disposed around the stud 15 are a series of inclined,arcuate ratchet. steps 16 which it will be seen serve to provide a snapaction for the switch mechanism. Two of the opposed steps are adapted toreceive the fixed contacts 17 and 18 that are spaced from each other bythe narrow ratchet steps 16'.

The terminal end 19 of the fixed contact 17 is provided with a tappedopening 20 for receiving a terminal screw 21 and is of such a size andshape that it may be seated in the aperture 22 formed in the base 13.The hook portion 23 of terminal end 19 is arranged to be seated on theledge 24 of the base 13 near the aperture 22 to assist in supporting thefixed contact within the switch housing. Looking at Figure 7, there isan apertured boss 55 on the cover 14 which is adapted to receive the endof the terminal screw 21 as well as to mate with the terminal end 19 ofthe fixed contact 17 to insure that it is held firmly in place withinthe base 13. Thus, it will be seen that it is possible to connect a leadwire (not shown) to the switch mechanism by means of the terminal screw21 which has its head arranged outwardly of the switch housing.

Considering Figures 3 and 7 of the drawing, it will be seen that thefixed contact 18 has at one end a center contact strip 28 serving as thecenter contact for the screw shell socket 11. In Figure 3 of thedrawing, fixed contact 18 is shown seated on the ratchet step 16 andopposite the remaining fixed contact 1'7. A slot 29 is formed in oneedge of the base 13 and a similar slot 29 is formed in one edge of thecover 14 so that the strip 30 which connects the fixed contact 18 withthe center contact 28 is fitted within the said grooves 29 and 219 to becentrally located in the screw shell 11, as is best seen in Figure 6.

A rotary contactor 35 which serves as the movable contact between thefixed contacts 17 and 18 is provided with a central opening 36 so thatit may be fitted over the stud member of the base 13 to rotate withrespect thereto. Edgewise blades 37 are formed on opposite sides of thecontactor to have sliding engagement with the fixed contacts 17 and 18.The lower edge 38 of each blade 37 is inclined in the same manner as thefixed contacts 17 and 18 so that there is a fiat edgewise engagementbetween the movable and fixed contacts. Spaced between the blades 37 area pair of ratchet teeth 39 which are adapted to cooperate with theinsulating ratchet member 49 that is fitted over the stud 15 on top ofthe contactor 35.

The ratchet member 40 is of fiber material with a central pivotalopening 41 and a series of four ratchet openings 42 equally spacedaround the aperture 41. An integral arm 43 extends from one side of theratchet member 40 and it has an opening 44 containing the link member 45for making engagement with a pull-chain 46 of the usual construction. Anadjustable torsion spring 59 is also fitted over the stud 15 after theratchet member 40 is in place. The lower end 51 of the spring is shapedto fit into the pinhole 47 of the ratchet member 40 to fix that end ofthe spring with respect thereto. The opposite end 52 of the spring 50 isrounded to fit into one arm of the cross-shaped slot 53 formed in thecover member 14, as is best seen in Figure l.

The purpose of the cross-shaped slot 53 in the cover member 14 is topermit the adjustment of the spring tension of the torsion spring 50.Thus, it is possible to use a special tool (not shown) having abifurcated end to depress the spring 50 until the rounded end or tongue52 is free of the slot 53 and then by turning the spring the necessaryamount to obtain the desired spring tension after the switch isassembled in the switch housing. When the adjustment is correct, thespring may be released by withdrawing the tool so that the rounded end52 of the spring is again seated in one of the arms of the cross-shapedslot 53. By using such a slot it is possible to obtain the fineness of aquarter-turn adjustment.

The method of assembling this switch mechanism is quite simple in thatthe base member 13 may be placed on the operators work bench and thefixed contacts 17 and 18 are dropped onto their respective ratchet steps16 in the base 13. Then in quick succession the rotary contactor 35 isfitted over the end of the stud 15, and in turn the ratchet member 40,torsion spring 50, and finally the cover member 14 are assembled to forma completely enclosed switch mechanism. After this it is merelynecessary to adjust the spring tension of the torsion spring so that theswitch will be ready for use. The switch is operated by moving therotary contactor 35 into and out of engagement with the fixed contacts17 and 18. This movement is effected by exerting a pulling force on thepull chain 46 which tends to oscillate the member 41! about the stud 15.The ratchet teeth 39 of the contactor 35 are seated within the ratchetopenings 42 of the ratchet member 40 so that any counterclockwisemovement of the member 40 likewise moves the eontactor 35.

When the line of force of the pull chain 46 extends through the pivotalaxis of the stud 15, any additional pull on the chain will beinefiective in rotating the ratchet member 40. When the chain 46 isreleased, the torsion spring 50 will take over, since it was tensionedby the counterclockwise movement of the ratchet member 40, and it willtend to return the member-4t) to its normal position. During this returnmovement of the ratchet member 40, the contactor 35 remains fixed due tothe shape of the ratchet steps 16 and 16 in the base 13. Consequently,the ratchet openings 42 of the ratchet member 40 will move out ofdriving engagement with the ratchet teeth 39 of the contactor 35. Theraised ratchet teeth 39 also serve as a detent mechanism in cooperationwith the ratchet openings 42 of the member 40 so that normally the teeth39 are disposed within opposite ratchet openings 42. Thus, when apulling force is applied to the pull chain 46, the contactor 35 will bedriven by the movement of the ratchet member 40 to make or break theelectrical circuit through the fixed contacts 17- and 18. The screwshell 11 has a. partial base 56, as seen in Figure 7, which is nearlycut-away by the enlarged central opening 57. A pair of lanced tabs 58are struck out f the base 56 to lie opposite and parallel to each other.The tabs 58 of the screw shell 11 are each provided with aligned slots59 so that when the switch parts are assembled in the base member 13 andthe cover member 14 is disposed thereover, the tabs 58 of the screwshell ll may be arranged tostraddle the parts 13 and 14 at a point wherethere are openings 60 and 61 in the base 13 and cover 14 respectively.Thus, a ground contact such as.

strip 62 may be fitted through the slots 59 in the tabs 58 as well asthrough the openings 60 and 61 in the housing parts. Finally, the freeend of strip 62 is bent or twisted to complete the assembly and finallyhold all of the parts in assembled relation. The terminal end 63 of theground contact 62 is bent at a right angle and provided with a tappedopening 64 for receiving the terminal screw 65 so that a second leadwire (not shown) may be connected to the switch mechanism for completingthe circuit through the switch.

Itwill be appreciated by one skilled in this art that I have provided asimplified design for a ratchet-type switch mechanism having a rotarycontactor with edgewise blades for making and breaking contact with thefixed contacts of the switch mechanism. Because of the use of thesecdgewise blades, it is possible to provide narrow grooves between thefixed contacts so that when the blades are seated therein, theclearances between the blade andthe side walls of the grooves are soslight as to prevent an electrical are from spreading and burning theswitch parts. it is this feature which has brought about. the new andunobvious result of extinguishing the arc and extending the life of theswitch as well as making it possible to obtain a higher electricalrating for the switch at a minimum cost.

A second important feature of this invention is the unique manner ofsupportingthe fixed contact 17 within the base by utilizing the hookmember 23 and ledge 24 which cooperates with the apertured boss 55 inthe cover 14 to hold the terminal end 19' firmly in place in the switchhousing. Also, the adjustable torsion spring means is anotherimprovement which contributes to the high quality of this device.Likewise, the simple ground contact 62 and the mannerin which it is usedto finally assemble this switch mechanism is a unique feature of thispresent invention.

While this invention has been disclosed as combined in a lamp socketinterior, it should be appreciated that this ratchet-type switchmechanism has general utility in the switch art and that it could alsobe used in feed through switches for portable electrical cords and anyplace where a rotating movable contactor may be used to advantage.

Modifications of this invention will occur to those skilled in this artand it is to be understood, therefore, that this invention is notlimited to the particular embodiments disclosed but that it is intendedto cover all modifications which are within the true spirit and scope ofthis invention.

What Iclaim as new and desire to secure by Letters Patentof the UnitedStates is:

l. Ina-.rotary, switch comprising a hollow housing having a series ofarcuate ratchet steps formed on an inner wall surface of said housingcentered around an inwardly projectingstud member, fixed contactslocated on-ppppsite steps of the housing and being-separated by arcuatesteps of relatively narrow width, and a rotary contactor mounted oversaid stud for making and breaking the circuit through the fixedcontacts, said contactor having a pair of contact blades oppositelyarranged thereon for edgewise engagement with the fixed contacts, thesaid edgewise blades of the rotary contactor serving to open the switchwhen positioned in the arcuate steps of narrow width, whereby the smallclearances between the edgewise blades and the side walls of the narrowsteps act to extinguish the are formed between the blades and the fixedcontacts.

2. In a rotary switch comprising a hollow housing having a series ofarcuate ratchet steps formed on an inner wall surface of said housingcentered around an inwardly projecting stud member, fixed contactslocated on opposite steps of the housing and being separated by arcuatesteps of relatively narrow width, and a rotary contactor mounted oversaid stud for making and breaking the circuit through the fixedcontacts, said contactor having a pair of contact blades oppositelyarranged thereon for edgewise engagement with the fixed contacts, and anoscillating ratchet member arranged over the said stud member fordriving engagement with the said rotary contactor, and adjustable springmeans for returning the insulating ratchet member to its normal startingposition once it is released from manual control, the said edgewiseblades of the rotary contactor serving to open the switch whenpositioned in the narrow arcuate steps whereby the small clearancesbetween the edgewise blades and the side walls of the narrow steps actto extinguish the arc formed between the blades and the fired contacts.

3. A rotary switch as recited in claim 2 wherein the spring means has atongue portion seated in an opening in the outer wall of the switchhousing so that the tension of the spring means may be adjusted afterthe switch is completely assembled in the switch housing.

4. In a rotary switch comprising a hollow housing formed of a basemember and a cover member, a series of arcuate ratchet steps formed onan inner wall surface of said base and centered around an inwardlyprojecting stud member, fixed contacts located on opposite steps of thebase and being separated by arcuate steps of relatively narrow width,one of said fixed contacts having a terminal end seated over an openingin the base so that a terminal screw may be threaded therein, and arotary contactor mounted over said stud for making and breaking thecircuit through the fixed contacts, said contactor having a pair ofcontact blades oppositely arranged thereon for edgewise engagement withthe fixed contacts, the said edgewise blades of the rotary contactorserving to open the switch when positioned in the arcuate steps ofnarrow width, whereby the small clearance between the edgewise bladesand the side walls of the narrow steps act to extinguish the are formedbetween the blades and the fixed contacts, and a ratchet mechanism fordriving engagement with the said rotary contactor upon the manualactuation of the switch, the said cover member having a boss whichengages the said terminal end of one of the fixed contacts to hold itfirmly within the switch housing.

5. In a pull chain operated lamp socket interior comprising a hollowhousing formed of a base member and a cover member, a series of arcuateratchet steps formed on an inner wall surface of said base and centeredaround an inwardly projecting stud member, fixed contacts located onopposite steps of the base and being separated by arcuate steps ofrelatively narrow Width, one of said fixed contacts having a terminalend seated over an opening in the base so that a terminal screw may bethreaded therein, one portion of said terminal end seated on a ledge onthe base member adjacent the said opening, the said cover member havinga boss which engages the said terminal end of one of the fixed contactsto hold it firmly within the switch housing, and a rotary contactormounted over said stud for making and breaking the circuit through thefixed contacts, said contactor having a pair of contact bladesoppositely arranged thereon for edgewise engagement with the fixedcontacts, the said edgewise blades of the rotary contactor serving toopen the switch when positioned in the arcuate steps of narrow width,whereby the small clearances between the edgewise blades and the sidewalls of the narrow steps act to extinguish the are formed between theblades and the fixed contacts, and a ratchet mechanism for drivingengagement with the said hotary contactor upon the manual actuation ofthe said pull chain, and an adjustable torsion spring having alongitudinally extending tongue at one end extending into a slottedopening through the said cover member so that its tension may beadjusted from the outside after the switch is completely assembled, anda screw shell fitted over the said base and cover members and fixedthereto.

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